The web used to be a barren wasteland in which you could buy 37 varieties of cheese grater and view every webpage in full geocities glory(http://wonder-tonic.com/geocitiesizer/ ). Other than that there wasn't much online that you couldn't get offline. There were online encyclopedias but those were just electronic versions of what you could get at the library.
As the web grew we started gaining advanced tools that were not available before. Online encyclopedias evolved into Wikipedia which sacrifices elements of reliability for open access. I use Wikipedia more than encyclopedias now because I check the reliability of the information after I find it. The upsurge in available information is a huge resource for students. Although I do not use twitter I recognize the significance of twitter, facebook and social networking in general. It has allowed us to connect in ways that were never possible before. I think students can use these tools to collaborate.